In conventional lighting systems and lighting devices like luminaires, it is common to put the light sources in a standby mode, when they are not in use. While in standby mode, the lighting devices are capable of a limited functionality. The most important functionality is listening to upcoming control commands that may request the lighting device to wake up and go to normal drive mode.
WO2008/134433 discloses a lighting system in which an Ethernet computer network is used to provide power to one or more lighting devices that are connected directly to the Ethernet. The system utilizes the IEEE standard Power over Ethernet (PoE). The lighting devices may include light emitting diodes (LEDs), fluorescent lamps, high-intensity discharge (HID) lamps and/or exit signs. By providing power to the lighting devices via the Ethernet, a separate connection to a power supply for the lighting device is not necessary. One Ethernet cable is thus applicable for transporting both data and power in the lighting system. Further, to save energy a zero standby power can be realized for an individual lighting device by switching off its corresponding Ethernet port which is utilized for providing the power. A computer, through the Ethernet, monitors and controls when lighting devices should be turned off to conserve energy when the lighting is not required, such as after-hours, etc. Further functionality like timed lighting can also be controlled by the computer.
While the system described above is generally effective in accomplishing its purpose, it requires a large and complex infrastructure, and an omniscient management computer. Further, the system is a quite blunt tool in handling standby and startup of lighting devices in which different driving is required in particular when employing a plurality of different types of light sources in the lighting devices of the lighting system. This may result in unsynchronized control of the lighting in a room and the occurring of annoying time delays in the lighting of the lighting devices.